Centrifugally operated actuator for switches and other trip mechanisms



g- 1966 w. c. HUNGERFORD 3,267,229?k CENTRIFUGALLY OPERATED ACTUATOR FOR SWITCHES AND OTHER TRIP MECHANISMS Filed Aug. 22, 1963 2 Sheets-Sheet .1,

INVENTOR. WILLARD C. HUNGERFORD BY WSM Aug. 6, 1966 w. c. HUNGERFORD 3, 7, 9

CENTRIFUGALLY OPERATED ACTUATOR FOR SWITCHES AND OTHER TRIP MECHANISMS Filed Aug. 22, 1963 2 Sheets-Sheet 2 INVENTOR WILL ARD C. HUNGER FORD BY Mam United States Patent 3,267,229 CENTRIFUGALLY OPERATED ACTUATOR FOR SWITCHES AND OTHER TRIP MECHANISMS Willard C. Hungerford, Honolulu, Hawaii, assignor to Willard Instrument C0., El Cajon, Calif. Filed'Aug. 22, 1963, Ser. No. 303,870 2 Claims. (Cl. 20080) The present invention relates generally to a centrifugally operated actuator and more particularly to such an actuator used for opening and closing a microswitch at predetermined speeds.

The primary object of this invention is to provide an improved actuator for microswitches which will require a minimum of space axially when mounted on a rotary shaft.

A further object of this invention is to provide an improved actuator which is adapted to be mounted in multiple or stacked arrangement axially of a rotatable shaft.

It is a still further object of this invention to provide a centrifugal actuator having improved means to vary the speed at which the actuator will trip an associated mechanism.

Finally it is an object to provide a centrifugally operated actuator of the aforementioned character which is simple and convenient to use and which will give generally eflicient and durable service.

With'these and other objects definitely in view, this invention consists in the novel construction, combination and arrangement of elements and portions, as will be hereinafter fully described in the specification, particularly pointed out in the claims, and illustrated in the drawings which form a material part of this disclosure, and in which:

FIGURE 1 is atop plan view of the actuator and microswitch with the actuator in the low speed operating position and the microswitch open.

FIGURE 2 is a view similar to FIGURE 1 with the actuator in the high speed position and the microswitch closed.

FIGURE 3 is an elevation view with part of the supporting structure for the actuator broken away.

FIGURE 4 is a section on the line 44 of FIG- URE'l.

FIGURE 5 is a section on the line 55 of FIG- URE 2.

FIGURE 6 is a top view of the weight shown in FIGURE 5 with part of the top plate cut away.

FIGURE 7 is an elevation view showing how the actuators and microswitches may be stacked axially along a shaft.

Referring now to the drawings, in which like reference numerals are used to denote similar parts throughout the several views, the centrifugally operated actuator is indicated generally by the reference numeral 20 while the trip mechanism for the microswitch is indicated by the numeral 70. While I have shown my actuator used with a microswitch mechanism it is to be understood that it may be used with any mechanism in which the operating cycle varies between two speeds of rotation of a power driven shaft.

CENTRIFUGALLY OPERATED ACTUATOR The operating elements of the actuator 20 are mounted on a generally circular plate member 22 which is fixedly secured in any conventional manner to shaft 24. Extending upwardly from plate 22 :are a plurality of segmental flanges 26, 28, 30, and 32 the purpose of which will be hereinafter described. Fixed to the plate 22 at diametrically spaced points and extending upwardly therefrom are a pair of pivot pins 34 and 36. Journalled on pivot pin 28 by suitable antifriction bearings 38 is a flyweight arm indicated generally by the reference numeral 40 and a similar flyweight arm 42 is journalled on pivot pin 36. Arms 40 and 42 are connected together to move in unison -by inflexible parallel links 44 and 46. Link 44 is pivotally connected to flyweight 40 by stud 48 while a similar stud 50 connects the other end of link 44 to flyweight 42. Link 46 is similarly connected to flyweight 40 by stud 52 and to flyweight 42 by stud 54. Since flyweight arms 40 and 42 are similar the description of one only will suflice.

Arm 40 is of generally dog-leg shape having a long arm 56 and a short arm 58 and is formed of upper and lower spaced plates 60 and 62 respectively connected together by studs 48 and 52. Plates 60 and 62 are spaced by collars 64 and 66 which fit over studs 48 and 50 respectively.

Upper plate 60 is provided with a first or low speed cam portion 72 and a second or high speed cam portion 74. As shown in FIGURE 4 high speed cam portion extends generally in the plane of plate 60 while the low speed cam portion is formed by bending plate 60 downwardly and then outwardly. With the actuator at rest low speed cam 72 extends beyond the periphery of plate 22 while the radial extent of high speed cam 74 is generally coextensive with the periphery of plate 22 for a purpose which will be later described.

It is frequently desirable to change the moment of inertia of the flyweight arms to permit the high speed cam to operate within a limited range of high speeds. This is accomplished by providing an adjustable weight on the short leg 58 of the flyweight arm. In the par' ticular form shown this weight takes the form of a truncated cylinder 76 shown in detail in FIGURES 5 and 6. This weight is mounted between upper plate 60 and lower plate 62 and is provided with journal portions 78 and 80 rotatably received in cylindrical openings 82 and 84 in the top and bottom plates respectively. The upper journal 78 is provided with a slot 86 for reception of a suitable tool for rotating weight 76.

The top surface of plate 60 has formed therein, around the opening 8 2, a series of equally spaced marks or calibrations 88 here shown as twelve in number although any suitable number may be used. These marks 88 are calibrated for different speeds so that adjust-ment of the weight 76 will vary the moment of inertia of arm 40 and change the speed at which the high speed cam is operative. After the weight has been set at the particular speed desired a portion of the upper plate is peened into the slot 86 as shown at 89 in FIGURE 1. This locks the weight in position for the particular speed desired. Further adjust ment may be made if desired by removing metal portion 89 thereby freeing weight 76 for rotary adjustment.

Tension spring 90, one end of which is connected to the flyweight arm at 92 and the other end of which is connected to plate 22 at 94, exerts a force on the flyweight arm tending to rotate itin a clockwise direction around pivot pin 34. This retains the flyweight armin the low speed position until a predetermined speed has been reached, as determined by the position by weight 76, at which time the centrifugal force exerted on the flyweight arm overcomes the tension of the spring and the flyweight arms move to the position shown in FIGURE 2.

MICROSWITCH T-RIP MECHANISM The particular microswitch trip mechanism will now be described. Suitably mounted within housing 96 is a conventional microswitch structure with a switch actuating plunger 98 extending outwardly from housing 96. Housing 96 is secured by any well known means to support plate 99. Also mounted on plate 99 is a stud 100. Journalled for oscillation on the stud 100 is the trip mechanism generally indicated by reference numeral 70. This trip mechanism includes an upper arm 102 and, angularly spaced therefrom, a lower arm 104. The ends of these arms may be rounded or angled as clearly shown. Suitable stop arms 106 and 8 are provided to limit the oscillatory movement of trip mechanism 70 by engagement with pin 1'10 fixedly mounted in plate 99.

To actuate the microswitch through the trip mechanism 70 a spring arm 11?. is provided, one end of which is suitably secured to base 99 .at 114. Adjacent the other end spring arm rests on switch plunger 98 and is then turned angularly, as seen in FIGURE 1, to provide a cam portion 116. A follower member in the form of a sleeve 118 is rotatably mounted on stud 120' which is suitably secured to lower arm 104.

OPERATION With particular reference to FIGURES 1 and 2 the operation of my improved centrifugal operator will now be described. In the at rest or low speed position shown in FIGURE 1 the flyweight arms have been rotated clockwise by springs 90 so that low speed cam portion 72 projects outwardly beyond the periphery of plate 22 and in position to engage lower arm 104 of the microswitch trip mechanism. This permits spring 112 to assume the position shown in FIGURE 1 with the microswitch plunger 98 elevated and the microswitch circuit open. Flanges 26 and 30 act as limiting stop members for the low speed cam portions 72. Rotation of the shaft 2 4 in the direction of arrow 122 will have no effect upon the flyweights until the speed of the shaft reaches the point, determined by the setting of eccentric weights 76, at which the centrifugal force acting on the flyweights overcomes the tension of springs 90. At this point the flyweights will pivot in a counterclockwise direction about studs 34 and 36, respectively. Since the springs 90 are connected to the arms between the fiyweights and the pivots of the arms and each spring extends across plate 22 generally alongside its respective arm, as shown in FIG- URE 1, the swinging motion of the arm will move the spring across the plate toward the pivot of the arm. The action is similar to that of a toggle but does not progress to the dead center position since the arm motion is very limited. However, the elongation of the spring is small and, due to the lateral translation of the spring, the rate of elongation decreases progressively, while the inertia of the outwardly moving flyweights increases substantially linearly. Thus the centrifugal inertia of the fiyweights increases much more rapidly than the resistance of the springs. Low speed cam 72 will be withdrawn to the position shown in FIGURE 2. At the same time upper or high speed cam 74 will move outwardly to a position where it engages arm 102 of trip mechanism 70. Arm 102 will be caused to rotate in a clockwise direction on stud 100, carrying with it arm 104. Cam roller 118 will roll on the surface of cam 116 at the same time depressing the spring arm and the switch plunger 98 thereby closing the circuit in the microswitch. The end of cam 11 6 engages cam roller 1 at a point where the spring 112 will 6 be locked in the position shown in FIGURE 2 until such 4 7 time as the speed drops to the point at which the low spec cam will come into operation.

In FIGURE 7 I have shown by way of example a typical installation of a plurality of centrifugal actuators 20 installed along a rotary shaft 24. Each of these actuators operates its own microswitch and the actuators may be calibrated to open or close the microswitches 'at varying speeds. The complete assembly is mounted in a suitable housing or framework 124. It will be apparent from this figure that centrifugal operator 20 requires a minimum of axial space and is therefore suitable for installations where axial space is limited.

It is understood that minor variation from the form of the invention disclosed herein may be made without departure from the spirit and scope of the invention, and

a flyweight mounted on each of said offset arm portions;

each of said arms having a high speed cam extending outwardly from the other end thereof; said arms being movable between a first position with said low speed cams projecting from said plate and a second position with high speed cams projecting from the plate due to centrifugal action on said flyweights; stop means on said plate to limit the motion of said arms at said positions; means for urging said arms to said first position, comprising a pair of tension springs each connected at one end to a point on one of said arms between the pivot of the arm and the flyweight, the other end of the spring being secured to said plate with the spring extending substantially alongside and adjacent to the respective arm, whereby motion of said arms due to centrifugal force will move the springs closer to the pivots of the respective arms. 2. An actuator according to claim 1 wherein said flyweights are rotatably adjustable on said arm portions and are unsymmetrical about their axes of rotation to change the moment of inertia of the weights.

References Cited by the Examiner UNITED STATES PATENTS 358,297 2/1887 Y Quint 73540 1,401,587 12/1921 Cornwall 200 1,855,703 4/1932 Cloud 200-80 2,831,671 4/1958 Leonard 73-548 X OTHER REFERENCES Zuleger: German application, 1,089,853, September 1960.

BERNARD A. GILHEANY, Primary Examiner.

H. A. LEWI'I IER, Assistant Examiner. 

1. A CENTRIFUGALLY OPERATED ACTUATOR FOR A TRIP MECHANISM, COMPRISING: A ROTARY SHAFT; A PLATE MEMBER FIXED ON SAID SHAFT NORMAL THERETO; A PAIR OF ARMS PIVOTALLY MOUNTED ON SAID PLATE DIAMETRICALLY SPACED ON OPPOSITE SIDES OF SAID SHAFT AND BEING PIVOTAL ABOUT AXES SUBSTANTIALLY PARALLEL TO THE SHAFT; LINK MEANS INTERCONNECTING SAID ARMS TO MOVE IN UNISON; EACH OF SAID ARMS HAVING AN OFFSET ARM PORTION AT ONE END EXTENDING GENERALLY TOWARD THE OTHER ARM; A FLYWHEEL MOUNTED ON EACH OF SAID OFFSET ARM PORTIONS; EACH OF SAID ARMS HAVING A HIGH SPEED CAM EXTENDING OUTWARDLY FROM THE OTHER END THEREOF; SAID ARMS BEING MOVABLE BETWEEN A FIRST POSITION WITH SAID LOW SPEED CAMS PROJECTING FROM SAID PLATE AND A SECOND POSITION WITH HIGH SPEED CAMS PROJECTING FROM THE PLATE DUE TO CENTRIFUGAL ACTION ON SAID FLYWEIGHTS; STOP MEANS ON SAID PLATE TO LIMIT THE MOTION OF SAID ARMS AT SAID POSITIONS; MEANS FOR URGING SAID ARMS TO SAID FIRST POSITION, COMPRISING A PAIR OF TENSIONS SPRINGS EACH CONNECTED AT ONE END TO A POINT ON ONE OF SAID ARMS BETWEEN THE PIVOT OF THE ARM AND THE FLYWEIGHT, THE OTHER END OF THE SPRING BEING SECURED TO SAID PLATE WITH THE SPRING EXTENDING SUBSTANTIALLY ALONGSIDE AND ADJACENT TO THE RESPECTIVE ARM, WHEREBY MOTION OF SAID ARMS DUE TO CENTRIFUGAL FORCE WILL MOVE THE SPRINGS CLOSER TO THE PIVOTS OF THE RESPECTIVE ARMS. 